Since there is no recorded history of the exact year they were buried, gold coins are fair game. The 100 year rules applies to archeological finds. Since a coin is not classified as archeological then I wouldn't worry about it. I have a 200 rifle cache buried that I have wanted to recover for over 20 years. That cannot be recovered without jumping through a ton of hoops. Good luck. Just be careful with whom you sell too and all will be good.